Phylum Mollusca Linnaeus, 1758 - molluscs
   Conchifera Gegenbaur, 1878 see Subphylum Conchifera Gegenbauer, 1878
     Cyrtosoma
       Class Gastropoda Cuvier, 1795 - snails and slugs
         Subclass †Archaeobranchia Parkhaev, 2001
           Order †Helcionelliformes Golikov & Starobogatov, 1975
             1 Superfamily †Yohelcionelloidea nom. null. see Superfamily Yochelcionelloidea Runnegar & Jell, 1976
             2 Superfamily †Helcionelloidea Wenz, 1938 see Superfamily Scenelloidea Miller, 1889